Development Of Ti (C, N) - Based Cermet Tool Based On Microwave Sintering Process And Its Cutting Performance

In this paper high speed cutting tool materials Ti(C,N) based cermets with high mechanical properties were fabricated by microwave sintering. Design of material composition and optimization of sintering process were conducted to perfect the cermets. The cutting performance of new type microwave sintered Ti(C,N) based cermets was studied when continuous dry turning hardened steels in comparison with those of ceramic cutting tool SG4 and cemented carbide cutting tools YT15、YS8.The paper thoroughly investigated effects of metal content and sintering temperature on the mechanical properties and microstructure of Ti(C,N)-WC-Mo2C-Co-Ni cermet material styles. It is can be found that a Ti(C,N) based cermet cutting tool material with 15% Co-Ni content which was sintered at 1550℃ for 10 min exhibited the optimum mechanical properties through the experiment. Its relative density、hardness and fracture toughness were 98.2%、15.49GPa and 10MPa·m1/2 respectively.The effects of Al2O3 particles content and sintering temperature on the mechanical properties and microstructure of Ti(C,N)-WC-Mo2C-Co-Ni-Al2O3 cermet material styles were also investigated. Addition of Al2O3 particles can improve hardness of materials remarkablely. However the high Al2O3 particles content could decrease the material’s fracture toughness. The experiment results revealed that a Ti(C,N) based cermet cutting tool material with 21% Al2O3 particles content which was sintered at 1550℃ for 10 min exhibited the optimum mechanical properties. Its relative density、hardness and fracture toughness were 98.6%、 17.78GPa and 8.65 MPa·m1/2 respectively.Cermet material system 44Ti(C,N)-10WC-10Mo2C-7.5Co-7.5Ni-21Al2O3 was chosen as cutting tool materials (TA) by the comparison of different materials system. The cutting performance of new type microwave singtered Al2O3 particles reinforced Ti(C,N) based cermet TA were investigated in dry turning three kinds of hardeded steels. The optimal cutting parameters of cutting tools were obtained by orthogonal design.In the test of turning hardened 45# steel (45±2HRC), the optimal cutting parameters of cermet cutting tool TA were cutting speed v=276m/min, cutting depth αp=0.3mm and feeding rate f=0.1mm/r. The tool life of cermet TA was about 40 min. The mean value of surface roughness (Ra) obtained by cermet TA was about 1.475μm. Both of these performance indexes were better than those of other three cutting tools. The wear of cermet TA was mainly located on rake face, including abrasion, adhesion and low diffusion wear and oxidation wear.In the test of turning hardened alloy steel 40Cr (50±2HRC), the optimal cutting parameters of cermet cutting tool TA were cutting speed v=120m/min, cutting depth αp=0.3mm and feeding rate f=0.1mm/r. The tool life of cermet TA was about 68.9min. The mean value of surface roughness (Ra) obtained by cermet TA was about 1.27p.m. Both of these performance indexes were better than those of other three cutting tools. The SEM micrographs of cermet TA revealed that micro tipping occurred during the cutting which decreases the machining quality. The wear mechanisms were micro tripping, brasion and adhesion wear on rake face of cutting tool.In the case of machining hardened tool steel T10A (60±2HRC), the optimal cutting parameters of cermet cutting tool TA were cutting speed v=60m/min, cutting depth ap=0.1mm and feeding rate f=0.1mm/r. When cutting high hardness materials, the life of TA cermet was dropped drastically. The life of cermet TA was only about 18.4min which was less than that of ceramic tool SG4. The mean value of surface roughness (Ra) obtained by cermet TA was about 0.99μm, which was superior to ceramic and cemented carbide cutting tools. The main failure mechanism of cermet TA was breakage of tool nose.